Apparatus for triggering restraint devices

ABSTRACT

An apparatus for triggering restraint devices includes crash sensors inside and outside of a control unit. The apparatus checks a crash signal of the crash sensors using a plausibility signal. To check the crash signal, the apparatus receives the plausibility signal from a vehicle sensor outside of the control unit, and then triggers the restraint devices as a function of the crash signal and the first plausibility signal.

FIELD OF THE INVENTION

The present invention relates to an apparatus for triggering restraintdevices.

BACKGROUND INFORMATION

German Published Patent Application No. 101 38 764 describes anapparatus for triggering a restraint device featuring crash sensorsinside and outside of the control unit. These crash sensors alsogenerate, in addition to the crash signal, a plausibility signal forchecking the crash signal.

SUMMARY

By contrast, an apparatus according to an example embodiment of thepresent invention for triggering restraint devices may provide thatvehicle sensors external to the system generate the plausibility signal.These are vehicle sensors located outside of the restraint system, thatis, they are neither located within the control unit, nor are they crashsensors located outside of the control unit. This may lead to speedadvantages, and may also lead to the complete elimination of theplausibility sensor.

Illustratingly, in the case of a side crash for instance, theplausibility may be assumed as given based on the information “vehicleis skidding” from a vehicle dynamics control system (ESP=electronicstability program). This may eliminate the waiting time prior to theacceleration reaching a central sensor in the control unit of therestraint system. This may represent a significant speed advantage andhence a faster triggering of restraint devices.

The apparatus may receive the plausibility signal from a knock controlsystem. The engine control unit continuously analyzes thestructure-borne sound signal at the engine block to detect engine knockand prevent it through control interventions. This signal may be checkedfor crash signatures for the purpose of deriving a plausibilization ofconventional triggering decision from it. This may eliminate theinstallation of an additional plausibility sensor.

If conventional plausibility sensors are used in addition, an overallplausibility signal may be generated through an OR operation on theplausibility signal of the crash sensor and of the vehicle sensor, whichmay be drawn upon in the triggering decision.

Exemplary embodiments of the present invention are shown in the Figuresand are explained in more detail in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an apparatus according to an exampleembodiment of the present invention.

FIG. 2 is a flowchart of a process running in an apparatus according toan example embodiment of the present invention.

DETAILED DESCRIPTION

Airbags have been part of the safety equipment of motor vehicles foryears. For triggering the pyrotechnic system, an algorithm is processedin the software of the electrical control unit. The input variables forthis algorithm may be sensor signals for detecting crash severity, forexample, acceleration signals and pressure signals, as well asinformation regarding occupancy, the closing of seatbelt buckles, etc.

To guard against false triggerings due to defective sensors, a principleto be followed is that the triggering decision must be plausibilized.This may be done via an independent sensor.

Two problems may be encountered in the plausibility concepts that maycurrently be in use:

1. Additional Costs

If, for example, an additional X sensor is used for plausibilizing theacceleration signal in the X direction, i.e., in the direction oftravel, costs may be incurred which may only support the safety concept,but which may provide no additional noticeable benefit to the customer.

2. Performance

If, for example, a peripheral sensor is used in the crash zone fordetecting a side crash, this may allow for a rapid triggering decision,but subsequently the system may still have to wait for the plausibilityof the safety sensor in the central unit. This is due to the fact thataccelerations are measurable there only a few milliseconds afterwards.

An example embodiment of the present invention may exploit informationquasi external to the system for plausibilizing the crash, instead ofusing a sensor of the restraint system for plausibilization. This mayeither lead to speed advantages or possibly even to the completeelimination of the plausibility sensor.

An example of such information external to the system is the signal ofthe ESP. Based on the information “vehicle skidding”, the plausibilitymay be deduced as given in a side crash, for example. This may eliminatethe waiting time prior to the acceleration reaching the central sensor.

Another alternative is the structure-borne sound signal of the knockcontrol system. This structure-borne sound signal, which is continuouslyrecorded, may be checked for crash signatures to identify a crash orcrash-related signals using pattern recognition. These may serve asplausibility signal.

FIG. 1 illustrates an apparatus according to an example embodiment ofthe present invention in a block diagram. A control unit 11, which maybe mounted at the tunnel of the vehicle, is connected to a side-impactsensor 10 via a first data input. Via a second data input, control unit11 is connected to a side-impact sensor 14 on the opposite side. In thiscontext, side-impact sensors 10 and 14 may be acceleration sensors.Alternatively, they may be pressure sensors that detect an adiabaticpressure increase in a hollow body in the side panels of the vehicleresulting from the deformation of this hollow body in the course of aside impact. Other deformation sensors may be used as well for thispurpose. Upfront sensors 12 and 13 attached to the radiator areconnected to control unit 11 via a third and a fourth data input. Theseare acceleration sensors that measure the acceleration at least in thedirection of travel. It is possible that they are also capable ofmeasuring accelerations transverse to the direction of travel, in the Ydirection, and in the vertical direction. Via a fifth data input,control unit 11 is connected to an ESP control unit 15, and via a sixthdata input, control unit 11 is connected to a knock control system 16.

Control unit 11 itself features a processor memory and its own sensorsto process a triggering algorithm for restraint devices 17 from thecrash signals of sensors 10, 12, 13 and 14. Restraint devices 17, towhich control unit 11 is connected via a data output, are airbags,seatbelt tensioners, a rollover bar, etc. Sensors 10, 12, 13 and 14 areinstalled remotely so as to be closer to the crash location. This mayallow for faster registration of crash signals. The algorithm running inthe processor of control unit 11, however, may also require plausibilitysignals for detecting failures or errors of crash sensors 10, 12, 13 and14. For this purpose, control unit 11 may either use signals of thecrash sensors themselves, for example, the mutual plausibility ofside-impact sensors 10 and 14, or also from sensors within control unit11 itself, that is, from central sensors. Signals of ESP control unit 15for controlling the vehicle dynamics and of knock control system 16 mayalso be used for plausibility. ESP control unit 15 indicates the stateof the vehicle dynamics and thus makes it possible to infer a possiblecrash. Knock control system 16 continuously monitors a structure-bornesound signal at the engine block, and this structure-borne sound signalmay also contain crash signatures allowing for the identification ofsuch a crash. If both or one of these are used, then possibly aplausibility via crash sensors may even be eliminated.

FIG. 2 illustrates a flowchart of the process running in an apparatusaccording to an example embodiment of the present invention. Thealgorithm for generating the triggering decision is executed in block20. To this end, control unit 11 receives triggering-relevant sensorsignals from sensors 10, 12, 13 and 14. At the same time, a plausibilitycheck is performed in blocks 21 and 22. This plausibility check may beperformed in block 21 on a conventional plausibility signal, i.e., on asignal of one of crash sensors 10, 12, 13 or 14 or of a central sensorin control unit 11. There, a mechanical switch, for example a Hamlinswitch, may be used as well. In addition, a plausibility check isperformed in block 22 on the basis of the signals of ESP control unit 15or of knock control system 16. The plausibility checks of blocks 21 and22 are combined in an OR operation in block 23. That is to say, if onlyone of blocks 21 or 22 indicates a plausibility signal, then the outputof OR gate 23 will yield a logical one, indicating the presence of aplausibility signal for a crash. OR gate 23 is connected to a firstinput of an AND gate 24. Block 20, which outputs the triggeringdecision, is connected to a second input. If the triggering decision isYES and a plausibility signal was detected, then the instruction to fireis given at the output of AND gate 24. If no triggering decision wasgenerated or if no plausibility signal is present, then no firinginstruction is issued.

Alternatively, it is possible to use only lower block 22, in which caseOR gate 23 may be eliminated. In that case, only the triggering decisionof block 20 and the plausibility check of block 22 are combined in anAND operation. If both are present, an instruction to fire is issued. Ifonly one is missing, no instruction to fire is issued.

1. An apparatus for triggering a restraint device, comprising: a controlunit directly connected to a plurality of crash sensors; and at leastone vehicle sensor located outside of the control unit, as a componentwithin a control system that is connected to the control unit andcontrols a vehicle function other than triggering of the restraintdevice; wherein the control unit is configured to check a crash signalgenerated by a first one of the plurality of crash sensors against aplausibility signal generated in response to an earliest-occurring oneof (i) a crash signal from another one of the plurality of crashsensors, and (ii) a crash signal from the control system, the controlunit triggering the restraint device when both the crash signalgenerated by the first one of the plurality of crash sensors and theplausibility signal are present.
 2. The apparatus of claim 1, whereinthe control system is a vehicle dynamics control system.
 3. Theapparatus of claim 2, wherein the first one of the plurality of crashsensors is a side-impact sensor, and the crash signal from the vehicledynamics control system is generated in response to a signal from the atleast one vehicle sensor.
 4. The apparatus of claim 1, wherein thecontrol system is a knock control system.
 5. The apparatus of claim 4,wherein the knock control system is configured to analyze astructure-borne sound signal for a presence of a crash signature and togenerate, independent of the plurality of crash sensors, the crashsignal as a function of the crash signature.
 6. An apparatus fortriggering a restraint device, comprising: control means directlyconnected to a plurality of crash sensing means; and at least onevehicle sensing means located outside of the control means, as acomponent within an additional control means that is connected to thecontrol means and controls a vehicle function other than triggering ofthe restraint device; wherein the control means is for checking a crashsignal generated by a first one of the plurality of crash sensing meansagainst a plausibility signal generated in response to anearliest-occurring one of (i) a crash signal from another one of theplurality of crash sensing means, and (ii) a crash signal from theadditional control means, the control means triggering the restraintdevice when both the crash signal generated by the first one of theplurality of crash sensing means and the plausibility signal arepresent.